Fluid blast circuit interrupter with sealing means for movable contact structure



Oct. 15, 1957 l. w. PATERSON 2,810,046

FLUID BLAST CIRCUIT INTERRUPTER WITH SEALING MEANS FOR MOVABLE CONTACT STRUCTURE Filed June 9, 1955 United States Ira W. Paterson, Milton, Mass., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application June 9, 1955, Serial No. 514,197

7 Claims. (Cl. 200-148) This invention relates to circuit interrupting devices and more particularly to are extinguishing means for use in connection therewith.

In the construction and operation of circuit interrupters, it is frequently necessary to provide means for extinguishing quickly the arc which is drawn between separable arcing contacts. This are is usually blown by blowout means, such as an air blast, into an arc chute which is arranged to quench the are by rapidly lengthening and cooling it in a predetermined manner.

The interrupting capacity of a circuit breaker depends to a great extent on the effective utilization of the interrupting blast of fluid under pressure. Heretofore in air blast circuit breakers difficulties have been experienced because of the excessive amount of compressed air permitted to escape through the space between the movable contact member and the surrounding arc chute structure. Reduction of the fixed clearance between the movable contact and the arc chute structure, to minimize escape ot air under pressure, was found to be impracticable.

In accordance with the invention claimed a fluid blast circuit interrupter is provided which employs a source of fluid under pressure, separable arcing contacts for establishing an are, a conduit for conveying a blast of fluid from the source adjacent the arcing contacts for extinguishing the are drawn upon separation of the contacts, and an insulating structure for enclosing the arcing contacts. The insulating structure is provided with a passage in which one of the contacts is reciprocally operated to form the arc and which partially encloses the reciprocating contact in a sheathlike manner. The insulating structure is provided with at least one tapered groove in the walls of the passage which houses or loosely retains a sealing rod arranged therein. During a contact opening operation the rod is pushed by air under pressure against the tapered sides of slot and against the movable contact to effectively seal the passage against loss of air under pressure.

A It is, therefore, one object of the present invention to provide a new and improved arc interrupting device.

Another object of this invention is to provide a new and improved fluid blast circuit interrupter which efiectively seals the interrupter against loss of fluid blast through contact openings.

A further object of this invention is to provide a new and improved air blast circuit interrupting device in which the passage opening in the structure for a movable contact is sufficiently large during a contact closing operation to provide room for possible contact misalignment but is effectively sealed against loss of air under pressure during a contact opening operation.

A still further object of this invention is to provide a new and improved sealing means for the contact openings of an air blast circuit breaker structure in which the friction between the stationary structure and the movable contact is reduced to a minimum.

\Objects and advantages other than those above set forthwill be apparent from the following description atent O when read in connection with the accompanying drawing in which:

Figure 1 is a diagrammatic view showing partly in cross section a fluid blast circuit breaker embodying the present invention;

Fig. 2 is a view in cross section of the embodiment illustrated in Fig. 1 taken along the line IIII;

Fig. 3 is a view in cross section of a modification of the sealing means illustrated in Figs. 1 and 2; and

Fig. 4 is a view in cross section of a further modification of the sealing means illustrated in Figs. 1, 2 and 3.

The fluid blast type of circuit interrupter shown by way of example in Fig. 1 comprises relatively movable arcing contacts such as fixed contact structure 7 of the finger type and a pivoted bladelike contact 8. The fixed contact structure may comprise a plurality of current carrying contacts and an arcing contact as is well known, and is electrically connected to one line terminal 9 of the breaker. The bladelike movable contact is connected to the other line terminal 10. Although in general, circuit breakers of the type considered in Fig. 1 are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawing and the circuit breaker will be described in detail as if it were of the single pole unit type.

The movable contact 8 is suitably connected to an actuating mechanism (not shown) through a connecting rod 11 for operating the movable contact between closed and open circuit positions.

For the purpose of extinguishing the are formed between the contacts when a power circuit connected thereto is opened, an insulating arc extinguishing structure 12 is arranged with respect to the contacts so that the arc is drawn at the entrance of the structure directly opposite a gas blast supply conduit 13. The conduit 13 is suitably connected through a blast valve (not shown) to a source of compressed fluid such as air, comprising for example a storage tank and compressor equipment (not shown).-

The are extinguishing structure may, for example, define a double barrel arc chute 14 comprising a first blast passage 15 for interrupting relatively high currents and a second blast passage 16 arranged parallel with and spaced apart from passage 15 for interrupting relatively low currents. The blast passages 15 and 16 have substantially uniform cross sections which may be rectangular or circular in form.

An insulating structure 19 which encloses the arcing contacts is arranged between the gas supply conduit 13 and the arc chute 14 for distributing the blast from the point where it arrives in highly concentrated form by the narrow blast supply conduit 13 to an arc chamber provided for enclosing the are upon inception thereof. The are chamber comprises arcing zones 20 and 21 which are spaced apart and situated at the upstream end of the double barrel arc chute 14. The blast divider structure 19 comprises a funnel-shaped portion 22 mounted immediately adjacent the supply conduit 13 and a pair of nozzles 23 and 24 which diverge from the diverging end of portion 22 toward chute passages 15 and 16.

The sides of the funnel-shaped portion 22 diverge at such a rate that the air expansion within the funnel is limited to the required minimum. The common axis 25 of supply conduit 13 and of funnel-shaped portion 22 of blast divider 19 is situated only slightly to the right of axis 26 of the first blast passage 15 of arc chute 14. Thus, the air blast reaching the downstream end of funnel-shaped portion 22 may pass into nozzle 23 with little restriction.

As illustrated in Fig. 1 the fixed contact structure 7 which is disposed edgewise to the blast projects almost to the longitudinal axisof nozzle 23 and is therefore sub- 3 j'ec'ted-to an intenseair blast upon operation of the arc extinguishing structure.

The Walls of the funnel-shaped portion 22 of the insulating structure 19, as illustrated in Fig. 1, define a diverging passage 29 ther'ethroughwhich accommodates the movable sickle-shaped blade contact 8. Thesewans clb'se- 1y surroundcontact S'i'na'shea'thlike-nianner and 'control the escape-of compressed air and arcproductsfro'm the nozzles 23 and 24 through passage 29. Passage-29may be provided with a plurality of'tr'ansver'salgrooves 39 whichtend to estahlisheddies inthesmall'flow of escaping airand arc'product's through passage 29; These eddies, in-tur n, tendto'minimizebut do not eliminate: the rate of thatflow.

A pair of probe electrodes 31 and32 may be mounted within blast passages 15- and'16, respectively, for aiding arc extinguishme nt: A current limiting resistor 33 interconnects electrode-31- andthe-rnu'ltiple finger contacts of the, fixedcontact structure 7; thus lowering the value of the arc current at' a predetermined time during arc extinguishment.

The circuit b'reaker'illustrated'in the drawing is shown with the cooperating arcing contacts in the closed circuit position: An opening operation is initiated by admission of air under pressure to supply conduit 13. The further flow of such air through passage 29 of funnel-shaped portion 22 of. blast divider 19 is at first impeded by contact" 8' which isdisposed edgewise to the blast and obstructs the passage 29. Actuation of the connecting rod 11 moves blade contact 8 toward the right to open the electric circuit.

As the blade contact 8 is separated from the fixed contact 7 an arc is drawn across the arcing zone 20 leading to the first blast passage 15 and substantially concurrently therewith a path is opened for a blast. of air of high intensity through thesuppIy conduit 13 and nozzle23.

of blast divider 19 to the first blast passage 15. This blast includes substantially all the air being supplied through.

conduit 13, and drives of loops the are from zone 20 into passage 15. Frequently the arc is interrupted in the first blast passage by the blast. of air flowing through nozzle 23. As the blade continues to move toward the right, the arc is extended into zone 21 if it is not already extinguished. The second blast passage 16 and nozzle 24 of blast divider 19 are uncovered and part of the arc is driven or looped from zone 21 into blast passage 16. by the blast from nozzle 24.

Inaccordance with the invention claimed and as shown in Figs. 1 and 2 of the, drawing, passage 29' is'provided with a plurality of grooves or slots 35 which are formed in the side walls of passage 29 and are arranged to extend substantially transversely to the direction of movement of arcing contact 8. Grooves or slots 35 are each provided with at least one tapered side 36 the plane surface of which forms an acute angle with the bladelike contact 8. The plane surfaces of the tapered sides 36 of slots 35 may also be described as diverging toward the leading end of the bladelike contact 8 during a contact opening operation. Sealing means comprising. a plurality of insulating rods 37 are arranged one within each of the slots 35 for effectively sealing passage 29 against loss of air under pressure during movement of contact 8 during a. contact opening operation. Rods 37 asshown in Figs. 1 and 2 may comprise solid cylindrical insulating members which are loosely arranged within slots 35 to extend longitudinally thereof with both ends of rods 37 extending beyond the edges of bladelike contact 8. During a contact opening operation rods 37 are pushed by air under pressure against the tapered sides 36 of slots 35 and bladelike contact 8 to effectively seal passage. 29 against loss of air under pressure. During a contact closing op eration rods 37 are pushed out of the Way, i. e., into. the larger volume portion of groove or slots 35, bythe contact blade 8 thereby allowing plenty of; room for any possible misalignment of. the. cooperating; arcing contacts.

The sealing rods 37 may be of any size and shape which will i prove most eifective' for'the sealing operation. The sloping surfaces of slots should form an angle with blade contacts 8 which will provide the most efiective seal with the least amount of friction between the sealing rods 37 and the contact blade 8 Fig. 3 illustrates a modification of the slots 35 shown in Figs; 1 andZwhereinthe insulating rodsv 37 are forced by the air under pressure directly againstithe slopingsi'de 40 of slot 41 and against the bladelike member 8;t'o'.form an effective air seal in passage 29. I

Fig. 4 illustrates a. further modification of the sealing means illustrated in Figs. 1', 2" and 3 wherein rod 42 is provided with aflat surface- 43. which engages the tapered fiat side 44 of slot to form an effective seal during a contact opening operation. When rod 42 is in sealing position surface 43 of rod 42 is substantially parallel with side 44 of slot 45. During contact closing operation rod 42 is pushedout of the way into the larger volume portion of the-slot in the samemanner as, rods 37 of'Fig's. 1', 2 and 3.

Although but a few embodiments of the present'invention have been illustrated and described it will be apparent'to those skilled'in the art that various changes and' modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A fluidblast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts for establishing anarc, aconduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an insulating structure for enclosing said contacts and providing a passage in which one of'said con-v tacts is reciprocally operated to form said arc,,s,aid. structure being provided with a groove in the walls of said; passage, and sealing means comprising a movable member arranged within said groove for effectively sealing said passage against loss of fluid under pressure during movement of said one of said contacts in contact opening direction.

2. A fluid blast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts for establishing an are, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, an insulating structure for enclosing said contacts and providing a passage in which one of said contactsis reciprocally operated to form said are, the walls. of said passagepartially enclosing said one of said con-.

tacts in sheathlike manner and being provided with a,

plurality of grooves, and sealing means comprising. a mov-v able member one arranged within each of some of said grooves for efiectively sealing said passage against loss of fluid under pressure during movement of said one of said contacts during contact opening operations.

3. A fluid blast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts for establishing an are, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, an insulating structure for enclosing said contacts and providing a passage in which one of said contacts is reciprocally operated to form said are, said structure beingv provided with slots in the walls of said passage extending substantially transversely to the direction of movement of said one of said contacts, and sealing meanscomprising a plurality of insulatingv rods loosely arranged one within each of said slots for eifectively' sealing saidpassag against lossof fluid under, pressure during move-.-

ment. of said one, ofsaid contacts during contact opening; operations.

4. A fluid: blast circuit interrupter comprising in combination asourceoffiuidunder pressure, separable arcs,

ing contacts for establishing an arc, a conduit for convey ing a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, an insulating structure for enclosing said contacts and providing a passage in which one of said contacts is reciprocally operated to form said are, said structure being provided with slots in the walls of said passage, each of said slots being provided with at least one tapered side the plane surface of which forms an acute angle with said one of said arcing contacts, and sealing means comprising a plurality of insulating rods loosely arranged one within each of said slots, said rods during a contact opening operation being pushed by the fluid under pressure against said tapered sides of said slots and said one of said arcing contacts to efli'ectively seal said passage against loss of fluid under pressure.

5. A fluid blast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts comprising a bladelike movable arcing contact for establishing an are, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said bladelike contact being disposed edgewise to said blast, an insulating structure for enclosing said contacts and providing a passage in which said bladelike contact is reciprocally operated to form said arc, said structure being provided with slots in the Walls of said passage extending substantially transversely to the direction of movement of said bladelike contact, and sealing means comprising a plurality of insulating rods loosely arranged within each of said slots for effectively sealing said passage against loss of fluid under pressure during movement of said bladelike contact during a contact opening operation.

6. A fluid blast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts comprising a bladelike movable arcing contact for establishing an arc, a conduit for conveying a blast of fluid from said source adjacent said contacts for extiguishing the are drawn upon separation of said contacts, said bladelike contact being disposed edgewise to said blast, an insulating structure for enclosing said contacts and providing a passage in which said bladelike contact is reciprocally operated to form said are, said structure partially enclosing said bladelike contact in sheathlike manner and being provided with slots in the walls of said passage extending substantially transversely to the direction of movement of said bladelike contact, each of said slots being provided with at least one tapered side the plane surface of which diverges toward the leading end of said bladelike contact during a contact opening operation, and sealing means comprising a plurality of insulating rods loosely arranged one within each of said slots, said rods during a contact opening operation being pushed by the fluid under pressure against said tapered sides of said slots and said bladelike contact to effectively seal said passage against loss of fluid under pressure.

7. A fluid blast circuit interrupter comprising in combination a source of fluid under pressure, separable arcing contacts for establishing an arc, one of said contacts being of bladelike shape and movable to open an electric circuit, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said bladelike contact being disposed edgewise to said blast, an insulating structure for enclosing said contacts and providing a passage in which said bladelike contact is reciprocally operated to form said are, said structure partially enclosing said bladelike contact in sheathlike manner and being provided with at least one slot in each of the side walls of said passage, said slots extending substantially transversely to the direction of movement of said bladelike contact and each being provided with at least one tapered side the plane surface of said side diverging toward the leading end of said bladelike contact during a contact opening operation, and sealing means comprising a plurality of insulating rods loosely arranged one within each of said slots, said rods during a contact opening operation being pushed by the fluid under pressure against said tapered sides of said slots and said bladelike contact to effectively seal said passage against loss of fluid under pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,283,717 Bartlett May 19, 1942 2,382,850 Bennett Aug. 14, 1945 2,604,563 Jansson July 22, 1952 2,604,565 Burnham July 22, 1952 

